Abstract
"Tatara" is a traditional box-type furnace in Japan and had produced iron from iron sand and charcol. In this Tatara there were two techniques which were called Zuku-Oshi and Kera-Oshi. Zuku means pig-iron and Kera means steel. The Tatara started in the latter half of six century and is continuing up to today. I am interested in when did the two techniques establish. So I tried to investigate the question with data of iron (pig-iron) image of Buddha making age and old document which is called "Kokon-Kajibiko". It is concluded that Zuku-Oshi has established regularly in Kamakura period (1192-1333). In Kera-Oshi case is the latter half of Muromachi period (1392-1573).
